Analysis of developmental genetics for phenylalanine content in indica-japonica hybrid rice (Oryza sativa L.) across environments

Developmental genetics of phenylalanine content in indica-japonica hybrid rice (Oryza sativa L.) have been studied through 7 indica rice crossed with 5 japonica rice by using the developmental genetic models and corresponding statistical approaches for quantitative traits of triploid seeds in cereal crops. The unconditional genetic model was used to analyze the cumulative genetic effects (from flowering to a specific time) along the developmental stages, and the conditional genetic model was used to analyze the genetic effects in one specially developmental stage from one filling time to another time (t -> 1 -> t). Results showed that phenylalanine content of indica-japonica hybrid rice was simultaneously controlled by the triploid endosperm effects, cytoplasm effects, diploid maternal effects and their genotype x environment interaction effects. Endosperm dominance effect, maternal additive effect and cytoplasmic effect were more important at the initial stage of rice development than endosperm additive effect and maternal dominance effect. With regard to the components of heritability, maternal and cytoplasm general heritability and their interaction heritability were higher for phenylalanine content at all 5 developmental stages. Respectively, it occupied 68.3, 92.4, 100.0, 100.0 and 78.9% among all the component of heritability. It was suggested that improving the phenylalanine content of indica-japonica hybrid rice would be more efficient when selection was based on maternal plants at early generations in rice breeding program.